Extension Study of Maintenance Treatment With Subcutaneous Immunoglobulin (IgPro20) for Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

Time to first CIDP relapse based on adjusted INCAT score, using the Kaplan-Meier estimator. Relapse is defined as an increase of at least 1 INCAT score point (except for the increase from 0 to 1 in the upper limb score only).

The INCAT score is a 10-point scale that covers the functionality of legs and arms, and has been successfully used to measure treatment effects in various CIDP studies. Scores for arm disability range from 0 ("No upper limb problems") to 5 ("Inability to use either arm for any purposeful movement"), and scores for leg disability range from 0 ("Walking not affected") to 5 ("Restricted to wheelchair, unable to stand and walk a few steps with help"). The INCAT (total) score is the sum of these 2 scores and ranges from 0 to 10. For the "adjusted" INCAT score, changes in the function of the upper limbs from 0 (normal) to 1 (minor symptoms) or from 1 to 0 were not recorded as deterioration or improvement because these changes are not considered clinically significant.

An adapted version of the MRC sum score as published by Kleyweg and the RMC trial group was used. With the MRC sum score, the following 8 bilateral muscle pairs were assessed, and individual muscle scores as well as the sum score documented: Shoulder abduction; Elbow flexion; Wrist extension; Index finger abduction; Hip flexion; Knee extension; Foot dorsiflexion; Great toe dorsiflexion. The MRC sum score ranges from 0 (paralysis) to 80 (normal strength) points.

The R-ODS is a recently published outcome measure that captures activity and social participation in subjects with Guillain-Barré Syndrome, CIDP, and monoclonal gammopathy of uncertain significance. The 24-item questionnaire covers a wide range of tasks of daily life that are each to be rated as "impossible to perform", "able to perform with difficulty", or "easy to perform" (scale of 0 - 2 points respectively). Items are sorted in order of increasing difficulty to perform, based on data from subjects with peripheral neuropathies (chronic inflammatory demyelinating polyneuropathy, Guillain-Barré Syndrome, or monoclonal gammopathy of uncertain significance) and subjects recruited at the university outpatient clinics of Rotterdam and Maastricht.

The hand-held Vigorimeter from Martin (Tuttlingen, Germany) is a device that measures the strength of small muscles in the hand, ie, grip strength. The subject squeezes a rubber bulb lying between the palm of the hand and the thumb and index fingers. The pressure is recorded via a rubber tube on a nanometer and expressed in kilopascal (kPa). At each assessment, the subject squeezes 3 times with each hand.